A PLR-based method to speed droop ratio estimation for primary frequency control

Abstract

The performance of primary frequency control (PFC) in power generation units is paramount important for power grids to suppress frequency fluctuations and preserve load-generation balance. The speed droop ratio is the most concerned primary frequency control performance index. This paper proposes a new method to estimate this index by extracting qualitative trends of involved signals. The proposed method is composed of three steps. The first step is to find the data segments including one PFC process from historical data of generated active power of power generation units according to variations in power grid frequency. The second step is to obtain piece-wise linear representations (PLR) of the selected generated active power data segments. The third step is to formulate the stages with PLRs, estimate the amplitude changes response stage, and calculate speed droop ratios for selected data segments. Simulated and industrial examples are provided to illustrate the effectiveness of the proposed method, and compare with two existing methods.